Sodium Hydroxide → HCID 67981931, compound

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Reaction Steps

Conjugated malonate 3a (10 g, 29.5 mmol) in THF (130 ml) is vigorously stirred with NaOH (4.8 g, 118 mmol) in water (120 ml) at 25° C. for 5 h. After addition of conc. NaHCO3 the mixture is extracted with tert-butyl methyl ether. The organic phase, which contains aldehyde 5, is discarded. The water phase is acidified with conc. HCl to pH 2 and extracted with tert-butyl methyl ether. The organic phase is dried over MgSO4, filtered and evaporated under reduced pressure giving 7.5 g (82%) of crude 1b with Z-configuration, which isomerizes upon standing slowly to an E/Z 1:1 mixture. Analytical data of the Z-isomer: 1H-NMR (400 MHz, CDCl3): δ0.96 (s, 6 H), 1.1 (d, 3 H), 1.4-1.6 (6 H), 1.56 (s, 3 H), 1.85-2.0 (4 H), 3.8 (m, 1 H), 3.9 (s, 3 H), 7.2 (d, 1 H) ppm. 13C-NMR (400 MHz, CDCl3): 19.41 (t), 19.42 (q), 19.8 (q), 26.4 (t), 28.56 (q), 28.57 (q), 32.7 (t), 34.8 (s), 36.0 (d), 36.8 (t), 39.7 (t), 52.6 (t), 124.0 (s), 127.3 (s), 136.7 (s), 161.0 (d), 166.6 (s), 167.3 (s). Z-Configuration determined on freshly prepared 1b by non-decoupled 13C-NMR-(method described in J. Med. Chem. 50, 1322-1334, 2007). HSQC- and HMBC-analysis in DMSO-D6. MS (DIP, El): m/z (%) 308 (M+, 65), 290 (10), 275 (20), 259 (24), 243 (76), 215 (29), 190(27), 175 (32), 158(100), 140 (43), 123 (29), 121 (22).

Provenance & Evidence